Ok, so having looked at the pdf, the assumption that the VCU is simply tacked on the front drive and only acts to lock the 'diffs' output to the front is incorrect because the rear drive passes through the 'diff' to the VCU too. Therefore the VCU does act to lock drive between both front and rear. In the senario that the front prop is removed the VCU is still active and in sensing what it percives as slip at the front, locks, transfering the drive to the rear!
 
warmers said:
Basically what i said a few days ago people must learn to listen or at least read Rave and understand it.
Click to expand...


The problem I believe is, that not all the information required to repair/diagnose the Borg Warner 44-62 is in Rave, hence supplemental manuals. And if the manufacturer wishes to confuse people by not using the correct terminology for parts it doesn't help much, either.
 
zzr1200 said:
Widget you posted a picture of a LT230 transfer case to support your arguement, TUT TUT, the P38 is fitted with a BW 44-62, at least lets use the correct pictures/infomation.
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To be fair its a Borg Warner 13-61-004, the case is the same as a 44-62, same epicyclic reduction set, same chain, same viscous unit. Its not an LT230 tsk.

zzr1200 said:
Land Rover say its a diff, incorrect, its a planetary gearbox, but Land Rover directly couple it to the VCU and use it to control slippage and allow for the difference in rotational speed between front and rear props, hence some T**t in Land Rover doesn't know what a diff is and what hes talking about.

Now Children, go to seperate corners of the room, open google, now type in " 1188291644.pdf " open with the "quick link" button and read, learn, then shake hands and be friends.......Bloody Children....:behindsofa:

PS. Happy New Year....:clap2:....:D
Click to expand...
Fair play. But I always assumed that anything that allowed differential motion could legitimately be called a diff.
 
Widget said:
I always assumed that anything that allowed differential motion could legitimately be called a diff.
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:5biagree:Meets the criteria to me too! Sure it's not a locking centre diff in the true LR sense, but it does the job, and that 1188291644.pdf explains it pretty well and particularly the confusion expressed by others as to how drive can still go to the rear with the front prop removed.
 
Widget said:
To be fair its a Borg Warner 13-61-004, the case is the same as a 44-62, same epicyclic reduction set, same chain, same viscous unit. Its not an LT230 tsk.
Click to expand...

A bit like complaining the parts aren't right when you've ordered them of the wrong parts list......:rolleyes:

Widget said:
But I always assumed that anything that allowed differential motion could legitimately be called a diff.
Click to expand...

It probably can. The problem is that if someone mentions a vehicle diff the generally excepted design is a Crown Wheel/Pinion with Sun/Planet Gears, planetary gears don't usually come into the equation.

kernowdragon said:
:5biagree:Meets the criteria to me too! Sure it's not a locking centre diff in the true LR sense, but it does the job, and that 1188291644.pdf explains it pretty well and particularly the confusion expressed by others as to how drive can still go to the rear with the front prop removed.
Click to expand...

Yep, someone has sat down and wrote a complete description that is understandable, its a pity its not included in Rave.

http://en.wikipedia.org/wiki/Differential_(mechanical_device)
 
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zzr1200 said:
The problem I believe is, that not all the information required to repair/diagnose the Borg Warner 44-62 is in Rave, hence supplemental manuals. And if the manufacturer wishes to confuse people by not using the correct terminology for parts it doesn't help much, either.
Click to expand...

Maybe me taking too much for granted. As a mechanic i know that the item listed as the differential cannot provide that function WITHOUT being coupled to the VCU. It is in fact the slipping plates in the VCU that give the differential effect and not the gearing it attaches to. Someone with less experience may not understand the principal of it. People don't need to fret though these days there are maybe not many Land Rover dealership mechanics that would understand it either. What we have in effect is an automatic self locking differential.
 
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wammers said:
Maybe me taking too much for granted. As a mechanic i know that the item listed as the differential cannot provide that function WITHOUT being coupled to the VCU. It is in fact the slipping plates in the VCU that give the differential effect and not the gearing it attaches to. Someone with less experience may not understand the principal of it. People don't need to fret though these days there are maybe not many Land Rover dealership mechanics that would understand it either. What we have in effect is an automatic self locking differential.
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Sorry Wammers, but after another evening studying RAVE, the BG overhaul manual and some other bit and pieces online I don't think you're right.

As far as I can tell the disputed 'diff' does provide true differential operation, and in theory you could remove the VCU and reconnect the front prop to the front output and maintain perfectly usable 4wd, with no wind up; only losing the locking function. If you study it, the front and rear shafts from the 'diff' (ie. the VCU inner and outer splines) must be capable of turning at different speeds otherwise there'd be no shear effect in the VCU to cause it to lock at higher speeds!
 
kernowdragon said:
Sorry Wammers, but after another evening studying RAVE, the BG overhaul manual and some other bit and pieces online I don't think you're right.

As far as I can tell the disputed 'diff' does provide true differential operation, and in theory you could remove the VCU and reconnect the front prop to the front output and maintain perfectly usable 4wd, with no wind up; only losing the locking function. If you study it, the front and rear shafts from the 'diff' (ie. the VCU inner and outer splines) must be capable of turning at different speeds otherwise there'd be no shear effect in the VCU to cause it to lock at higher speeds!
Click to expand...

Sorry your wrong. The fact that the VCU has two inputs is the clue. Also the VCU output IS the connection to the propshaft. If there was no VCU connecting either of the VCU input shafts to the prop if indeed that could be done would see the other one spinning freely with no drive. Have another look and try to understand. With the VCU in working condition the plates slide and give differential effect. With it siezed the unit is locked giving transmission windup and no differential effect. With it removed and both the input shafts welded together which you would have to do to get drive NO differential.
 
wammers said:
Sorry your wrong. The fact that the VCU has two inputs is the clue. Also the VCU output IS the connection to the propshaft. If there was no VCU connecting either of the VCU input shafts to the prop if indeed that could be done would see the other one spinning freely with no drive. Have another look and try to understand. With the VCU in working condition the plates slide and give differential effect. With it siezed the unit is locked giving transmission windup and no differential effect. With it removed and both the input shafts welded together which you would have to do to get drive NO differential.
Click to expand...

I must be totally misunderstanding the operation of the VCU then, as all the descriptions I've read, LR and otherwise, state that the VCU plays no part in transfering drive UNLESS the speed differential between front and rear reaches a certain point, at which stage it locks up and what was the rear input shaft becomes in effect the rear output as well, the front shaft being a pass-through through the VCU anyway.

With the VCU slipping under normal conditions it's simply allowing the diff to do it's job, obviously if it locks or seizes then you'll get wind-up. I still think that if you were to remove the VCU and create a connection between the front prop and the front output from the diff you'd still have 4wd, but without any locking effect.
 
kernowdragon said:
I must be totally misunderstanding the operation of the VCU then, as all the descriptions I've read, LR and otherwise, state that the VCU plays no part in transfering drive UNLESS the speed differential between front and rear reaches a certain point, at which stage it locks up and what was the rear input shaft becomes in effect the rear output as well, the front shaft being a pass-through through the VCU anyway.

With the VCU slipping under normal conditions it's simply allowing the diff to do it's job, obviously if it locks or seizes then you'll get wind-up. I still think that if you were to remove the VCU and create a connection between the front prop and the front output from the diff you'd still have 4wd, but without any locking effect.
Click to expand...

The VCU IS the diff. The cyclonic gear set pictured CANNOT provide differential effect without going through the VCU. That is why there is no differential action with a siezed VCU. Please no more on this my head hurts.
 
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err... guys?

1. am i going to eventually bollix it up more if i keep driving without the front prop?
2. why is it still whining even without the front prop and therefore (as far as i can understand) front and centre diffs taken out of the game? is my next stop the transfer box itself?
 
It must be just the way what I'm writing is coming across, cause what I'm trying to explain makes perfect sense to me, explains the function of the diff and VCU in partnership. What you seem to be saying is that effectively the RR system is just an overgrown freelander one?? I reckon next time I'm up your way we'll have to go for a pint with a pad and pencil, in the mean time I reckon we'll have to agree to disagree.
 
kernowdragon said:
It must be just the way what I'm writing is coming across, cause what I'm trying to explain makes perfect sense to me, explains the function of the diff and VCU in partnership. What you seem to be saying is that effectively the RR system is just an overgrown freelander one?? I reckon next time I'm up your way we'll have to go for a pint with a pad and pencil, in the mean time I reckon we'll have to agree to disagree.
Click to expand...

Ok fair enough. But forget the Land Rover description of the gear set as the differential unit. That is NOT a stand alone differential gear set, it only becomes so when coupled to the VCU. Please try to understand the gear set in conjunction with the vcu gives a differential effect. That is because of the movement allowed within the VCU to take up rotational differences. With a siezed VCU there is no movement and therefore no differential effect, that is why you get windup of the transmission. It is difficult to get things over i know, trying to explain things is not easy.
 
Right, it has been a good debate, I hoped someone would come up with a good explanation of how the transfer box, diff and VCU worked. I hate things that I don't understand. Since nobody came up with a logical explanation, I've done some digging and it's time to hold up my hands and say I was wrong There is a centre diff, not conventional (no bevel gears) but a diff none the less.

Some of the drawings are missleading and appear to show the VCU as part of the front output shaft, what they do not show clearly is that there is a foreward extension of the rear output shaft that goes to the centre of the VCU, so effectively the VCU is across both output shafts. This is why when the VCU seizes the diff is rendered ineffective.

I have now got a very good drawing of the centre diff which clearly shows the 2 concentric shafts onto which the VCU locates.

So there you go, I've learnt something and I was Wrong I was Wrong I was Wrong I was Wrong I was Wrong I was Wrong I was Wrong I was Wrong :doh::doh::doh::doh::doh::doh::doh::doh::doh:
 

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rasheed said:
err... guys?

1. am i going to eventually bollix it up more if i keep driving without the front prop?
2. why is it still whining even without the front prop and therefore (as far as i can understand) front and centre diffs taken out of the game? is my next stop the transfer box itself?
Click to expand...

If your VCU is siezed you should not be damaging anything with front prop removed. Buy yourself a mechanics stethecope jack the arse end up put it on axle stands, spin the transmission up and put scope to front and rear output bearings of Trannie box, diff and hub bearings. You should be able to find approximate location of the noise. If you hit the right spot it will stick out like a sore thumb. If you want to check front end for whining put prop on and you will have to lift all four wheels off the ground. Transfer box bearing do wear out, fairly easy to change if a little tedious. Diff bearings are not easy to change unless you know what your doing. Wheel bearings are easy to change if you have at least a 20 ton press. But get the scope and find out exactlly where the problem is. It maybe you have run with the VCU siezed for so long it has screwed the diffs up. Diffs don't usually whine unless they are being driven though.
 
Datatek said:
Right, it has been a good debate, I hoped someone would come up with a good explanation of how the transfer box, diff and VCU worked. I hate things that I don't understand. Since nobody came up with a logical explanation, I've done some digging and it's time to hold up my hands and say I was wrong There is a centre diff, not conventional (no bevel gears) but a diff none the less.

Some of the drawings are missleading and appear to show the VCU as part of the front output shaft, what they do not show clearly is that there is a foreward extension of the rear output shaft that goes to the centre of the VCU, so effectively the VCU is across both output shafts. This is why when the VCU seizes the diff is rendered ineffective.

I have now got a very good drawing of the centre diff which clearly shows the 2 concentric shafts onto which the VCU locates.

So there you go, I've learnt something and I was Wrong I was Wrong I was Wrong I was Wrong I was Wrong I was Wrong I was Wrong I was Wrong :doh::doh::doh::doh::doh::doh::doh::doh::doh:
Click to expand...

Is that not what i have been trying to explain, the differential action is dependent on the VCU being servicable. If it is not, then there is no differential action. The gear set is not a stand alone differential gear set, without the VCU it is a useful as tits on a Mars bar.
 
wammers said:
Is that not what i have been trying to explain, the differential action is dependent on the VCU being servicable. If it is not, then there is no differential action. The gear set is not a stand alone differential gear set, without the VCU it is a useful as tits on a Mars bar.
Click to expand...


Sorry, the diff would function fine without the VCU except there would be no diff lock, fine on road but as you say not much use off road. Me I would prefer a manual diff lock.
 
Datatek said:
Sorry, the diff would function fine without the VCU except there would be no diff lock, fine on road but as you say not much use off road. Me I would prefer a manual diff lock.
Click to expand...

No that is not the case. Without the VCU connecting the drive there would not be any.
 
Datatek said:
Right, it has been a good debate, I hoped someone would come up with a good explanation of how the transfer box, diff and VCU worked. I hate things that I don't understand. Since nobody came up with a logical explanation, I've done some digging and it's time to hold up my hands and say I was wrong There is a centre diff, not conventional (no bevel gears) but a diff none the less.

Some of the drawings are missleading and appear to show the VCU as part of the front output shaft, what they do not show clearly is that there is a foreward extension of the rear output shaft that goes to the centre of the VCU, so effectively the VCU is across both output shafts. This is why when the VCU seizes the diff is rendered ineffective.

I have now got a very good drawing of the centre diff which clearly shows the 2 concentric shafts onto which the VCU locates.
Click to expand...

That's exactly what I was trying to explain, I found the diagrams in the BW overhaul manual quite clear, particularly the one on p8. The 2 concentric shafts MUST already be capable of running at different speeds via the diff, or there would be no sheer forces created in the VCU gel to generate the locking effect when needed:doh:

Datatek said:
Sorry, the diff would function fine without the VCU except there would be no diff lock
Click to expand...

Therefore in theory you could conect front prop to front output shaft from diff and still get 4wd, but with no locking facility.

Thanks Datatek, I knew someone else would have to get it in the end.:)
 
kernowdragon said:
That's exactly what I was trying to explain, I found the diagrams in the BW overhaul manual quite clear, particularly the one on p8. The 2 concentric shafts MUST already be capable of running at different speeds via the diff, or there would be no sheer forces created in the VCU gel to generate the locking effect when needed:doh:



Therefore in theory you could conect front prop to front output shaft from diff and still get 4wd, but with no locking facility.

Thanks Datatek, I knew someone else would have to get it in the end.:)
Click to expand...

Tell you what, both of you strip one down and see how it works. The outer case drives the unit. Then we have planet gears, the planet carrier is splined to the rear output shaft, so the planet gears drive the rear axle, that then goes through the centre of the sun gear and is splined into the VCU. The sun gear shaft is splined to the outer flange of the VCU all power is transmitted through the VCU, which drives the front axle from its output, without the VCU it would be like having a broken half shaft on a standard diff and the diff would spin without doing anything. The cyclic gear set IS NOT a diff, it only becomes one when coupled to the VCU. IF THE VCU SIEZES UP THERE IS NO DIFFERENTIAL ACTION POSSIBLE.
 
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